Nightmotorsport Air Oil Separating Billet Valve Covers for Subaru EJ Engines

If you have changed plugs in your Subaru you know what a bitch it is!  Nightmotorsport has made the plug change much easier by relieving and adding this radius to the valve cover to make more room when getting the coil packs out to get to the plugs.  This makes a big difference and makes it worthwhile to get these valve covers just for this feature alone.  Just ask this guy who did a plug change at the track a few weeks ago!

The Nightmotorsport valve covers have cooling fins machined into them on the bottom where hot oil tends to accumulate.  They also look cool!

You can see the radiused edges of the valve cover and just how much more room it gives you to wiggle out the coil packs.  You can see what a difference this will make when the engine is installed in the car and the frame rail is blocking a direct shot at the coil packs.

The Nightmotorsport valve covers are a great-looking addition to Project GD STI and are also very functional.  Nightmotorsport says their valve covers eliminate the need for additional external air oil separators but Subaru engines spit so much oil that we are still going to run the IAG air-oil separator just to have super clean, oil-free blowby that will not contaminate the intake system.  We think that the Nightmotorsport valve covers will greatly help any Subaru from stock to highly modified.




    1. Initially, I thought so too but the owner of Nightmotosport came by and walked me through the features and I was very impressed with how well thought out they were, especially being a Subie owner and living through all the typical Subie issues.

  1. Curious to see an update at some point of accumulation in the IAG AOS after a track day. Love the content as always.

    1. Well the IAG AOS continually drains back into the crankcase which is a great feature, this way no oil is going to blow out of the engine!

  2. Wouldn’t such a part actually have the ability to free up power considering that the intake charge is no longer being contaminated with oil?

    Although, I have heard that Ferrari (and Mercedes?) were purposefully using oil consumption to make more power, although I am certain that they were tuning for the oil and using some pretty special oil additives.

    “Oil burns when it’s introduced into a gas-powered engine’s combustion chamber, which helps generate more power at the expense of, well, oil. In F1 today, fuel is heavily regulated by the FIA, but there’s a lot more flexibility with oil used. In practice, this means that teams can use certain additives to their advantage and create a more volatile fluid, helping with combustion.”

    1. Just reduce the likelihood of detonation, it’s not going to make more power, just let the engine make its intended power. Buring oil doesn’t make power, it has less BTU than fuel.

      1. Couldn’t you then run more aggressive timing and make your power that way? Similar to running higher octane fuel.

        I imagine that they only did it in F1 to get around the regulations. Not the way anyone would prefer to make power. Makes a mess.

  3. Is this item available in the 2.0 XT in my 2016 Forester? I am also curious best build for track day, (Road America Excludes 2016 Forester XT being a SUV, from running on their track, due to roll over by their experience), Brakes, Engine oil pump, oil pick up tube, oil pan, intake hosing, ect?

  4. So does this mean this could be installed instead of using an AOS like something like IAG AOS systems?

    1. We are still going to run an AOS on our motor with these valve covers. Night Motorsports says you dont have to.

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